As for interventionists:In case you need any greek flag, pls ask I will be happy to send you a correct flag.

As a generic rule: boslheviks used to have plain red flags. Later they added description of the unit etc. Whites used the czarist tricolour. If they belonged to special formationsor provisional governments they used to have their own banners and standards.

In the words of the character of Soviet children's film fairy tale, "I am not a magician - I'm just learning."

It's hard. Banners on those links that led above colleagues often have little relation to reality. I have quite a large collection of pictures of real flags of this period. But alas - they are not painted. For as long as miniatures are not suitable. I was going to paint them - but have no time!

Here are the banners, while not created for a particular photo, but it could exist in reality. Makhnovists, Red, Poles, Estonians.